work around to fix problem caused by copy of ways that is created when continue is used in style but no further routable way is added with 
this copy.

The code should to evaluate the restriction relation should be moved to 
RoadNetwork, this should reduce the complexity of the code.

git-svn-id: http://svn.mkgmap.org.uk/mkgmap/trunk@3183 25d90789-57f7-4ee0-8453-03a3dfeeeb22